Organic semiconductor based electronics relies on the noncovalent interactions induced organization of π-conjugated materials. To realize the extensive applications of organic electronic devices, both p and n-type organic semiconductors are essential. The p-type organic semiconductors have been thoroughly investigated over the past decades. However, the n-type organic semiconductors are lagging behind the performances of p-type semiconductors. Naphthalene diimides (NDIs) are among the most promising n-type semiconductors for organic material based electronic devices. NDI finds potential applications in organic field effect transistors, supramolecular switches, fluorescent chemosensors, electron and energy transfer systems. NDIs possess excellent characteristics for the construction of artificial photosystems. Planarity and high π-acidity of NDI system is ideal for face to face π-stacking.
Moreover the enhanced solubility offers better processability over other aromatic imides. In spite of its several merits the self-assembly of NDI is largely unexplored. For the potential applications of organic semiconductors in electronics, tuning the molecular interactions and hence the morphology to desired architectures is the need of the day.
Fabrication of new nanomaterials using natural building blocks such as amino acids, peptides and proteins is a fascinating area of research in recent years. Peptides based materials have been showed to be a great promise in the “bottom up” approach due to their diverse chemical and physical properties. They can be synthesized in large amounts and can be modified/decorated with functional elements which can be used in diverse applications. The simplest peptide assemblies are of dipeptide assemblies, which are the excellent building blocks for the formation of more complex nanostructures. Self-assembled nanostructures of dipeptide building blocks may find variety of applications such as in controlled drug delivery systems, in the field of tissue engineering, energy-related applications, biomineralisation, molecular electronics and biomaterial science.
Among organic electronic materials, 1,4,5,8-napthalenediimides (NDIs) are attractive due to their n-type semiconducting property and air stability. These are compact electron deficient class of aromatic compounds having tendency to form n-type semiconductor materials. NDI derivatives have got wide range of applications in biological, biomedical as well as in supramolecular chemistry. Its derivatives have been used as intercalators of DNA, chemotherapy, conducting materials, optical brighteners, electrophotography, fluorescent labelling systems, metalomacrocycles, models for the photosynthetic reaction centre (due to ease of synthesis and electron accepting properties), sensors (seven different positional isomers of dihydroxynaphthalene and DNA sensing) and anticancer agents. Because of their desired electronic, spectroscopic and enhanced solubility properties NDIs can act as ideal components for the creation of supramolecular functional materials (donor-acceptor complexes, barrels, catenanes and rotaxanes). The absorption and emission bands of NDIs are variable upon functionalization through the diimide nitrogens or via core substitution. Photophysical properties of N,N-dialkyl-substituted NDIs have been studied. The absorption and emission spectra of these compounds are mirror images to each other and readily aggregate in acetonitrile and in aqueous medium. In aromatic solvents (toluene) excimer-like emissions was observed due to ground-state aggregation. In the case of core substituted NDIs photophysical properties are different than unsubstituted ones, and are highly colourful and conducting functional materials.
1,4,5,8-Naphthalenediimides are neutral, planar, chemically robust, redox-active compounds usually with high melting points. Its derivatives can exhibit relatively high electron affinities, high electron mobility, and excellent chemical, thermal, and photochemical stabilities. Because of its electron transfer behaviour and the ability to tune molecular electronic properties through either variation of substituents on the imide nitrogen atoms or core substitution, they have been used as a building blocks for electronic and optoelectronic devices such as electron-transfer processes, photodetectors, organic light-emitting diodes, optical switches, dye lasers, and also as electron acceptors for studying photo induced energy.